Well, if you like the stinging experience of i.e. a pair of undies, here's the guide to how to achieve it.
The perfect solution - in my opinion - is actually sold in the same shop, where you buy your fabric, for sewing your kinky wear. They are most certainly NOT called "Cock'n'ball/pussy-spikes", but something as ordain as "Jersey press fasteners".
The ones I've used, are from "Prym", and the wrapper looks like this:
They are made to be mounted with the spikes through the fabric, and attached to the manufacturers intent, they are absolutely harmless!
Every single press fastener, consist of 4 parts (prior to assembly). There is
a 'male' part, a 'female' part - and the interesting ones - two rings with 5
spikes on either ring.
The intended assembly is, that you place the ring on one side of the fabric, and
the male/female part, on the other side, after which you - by the use of a
hammer and the tool delivered - makes the spikes pierce the fabric, after which
they are intended to deform safely on the inside of the male/female part.
At the pictures above, you can see the 4 parts, from 2 slightly different angles. the interesting parts - in an S&M-context - are the rings, with the spikes on. The male/female parts are, in this context, irrelevant.
Sewn onto the 'topside' of the
fabric...
and piercing through the fabric, from the 'bottom side'...
As you can see, it's possible to attach the rings to the 'topside' of the
fabric, as well as attaching them from the 'bottom side'.
However, if you attach them to the 'bottom side' you must be absolutely certain,
that the fabric cannot frawn, as the spikes otherwise will cause the fabric to
fall apart, because of the 5 spikes coming through the fabric.
Here I've used a red sewing line, in order to let you see it clearly, which could be difficult if I'd used a black sewing line and black fabric!
The fabric of choice - in my opinion - is the same, as used for i.e. swimsuits, which is frawn-free, elastic and pleasant to wear.
I have just completed a pair of 'Compression-bag panties' with spikes in the 'compression-bag' - a request for a guy, who is owned by a Domina whom I know.